Custom high-definition home entertainment systems can include one or more High-Definition Multimedia Interface (HDMI) matrix switches controlled by a central control system that allows a user to select among plural sources for video contents and among plural displays on which to view content. Such arrangements can allow different family members to view different contents in different rooms and allow a viewing in progress to follow a viewer who moves from one room to another. Such a matrix switch also allows individual sources to be seen simultaneously on more than one display. This arrangement also allows for all of the various video sources to be hidden in a remote location, leaving only the video display visible in the living areas.
The HDMI™ (High-Definition Multimedia Interface) standard developed and licensed by the HDMI consortium, is a high-speed digital interface for communicating audio and video signals between sources and sinks. HDMI sources can include HDMI-equipped cable boxes, satellite TV boxes, DVD players, Blu-Ray players, computers, HDMI-equipped smart phones, video cameras, hard-disk and memory-based media players, and other HDMI media sources, etc. HDMI sinks can include video display devices such as televisions or projectors and audio output devices.
HDMI video sources require direction from the sinks as to their capabilities in order to provide the proper video and audio data stream. The source will acquire this information from the sink by requesting the sink's Extended Display Identification Data (EDID) data array. EDID is a data structure used by an HDMI sink to describe its capabilities to an HDMI source. The EDID will specify, among other things, the display's capabilities in video resolution and frequency, audio support, and 3D capabilities. Based on this information, the source will provide the proper data stream.
An HDMI matrix switch may read the EDIDs from the various sinks in the system and generate a system wide EDID that is a set of lowest common denominators across the sinks. This system wide EDID is then presented to any source with whom a connection has been requested. This is necessary as, at any time, any sink can connect to any source, and the proper data must be sent to it. For example, if a system has several 1080p capable sinks but one sink capable of only 720p, the system EDID may require 720p for every sink since the 720p only sink can connect at any time and will not be able to display 1080p data.
3D video sources exacerbate this problem. If a matrix-switched high-definition home entertainment system contains at least one source that does support 3D and at least one sink that does not support 3D, the dilemma is how to develop the proper system EDID that will allow the 3D sink to request a 3D video stream while ensuring that the 2D only sinks can also access that source but request a 2D data stream. Using the lowest common denominator approach, 3D video support will not be allowed as not all displays can handle a 3D data stream.
A second 3D EDID related issue is how to handle the issue of sinks joining an existing connection. For example, a 3D sink joining a 2D connection will only provide a 2D display. Even more problematic is a 2D sink joining a 3D connection, in which case it will display distorted video or no video at all. These events will likely frustrate an end user and likely trigger a service call.